feat(render): add §5 body renderers as pure functions

TDD step 2: markdown-table rendering with the load-bearing escape order
(backslash, then pipe, then newlines to spaces with CRLF as one unit),
SQL value-to-text conversion (NULL empty, plain-decimal integers,
shortest round-trip floats, explicit bool/BLOB rejection — never silent
coercion), and the verbatim fenced block for http bodies. Table shape
and fenced-block form match the reference implementation byte for byte
ahead of the shared §11 golden fixtures.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QeqhJpYQyghASjiJo5EhGg

src/llm_ingestion_okf/errors.py

@@ -9,3 +9,7 @@ class IngestError(Exception):
 
 class ManifestError(IngestError):
     """The manifest failed fail-fast schema validation (ingest-spec §4)."""
+
+
+class RenderError(IngestError):
+    """A value cannot be rendered under the §5 body rules (never silent coercion)."""

src/llm_ingestion_okf/render.py

@@ -0,0 +1,68 @@
+"""Body rendering as pure functions (ingest-spec §5).
+
+Byte-compatible with the reference implementation: golden conformance (§11)
+freezes the markdown-table shape, the escape order, and the fenced-block form.
+"""
+
+from __future__ import annotations
+
+from collections.abc import Sequence
+
+from .errors import RenderError
+
+
+def sql_value_to_text(value: object) -> str:
+    """Convert one SQL cell value to its §5 text form (BEFORE table escaping).
+
+    SQL NULL → empty string; integers plain decimal; non-integral numbers in
+    shortest round-trip decimal form (repr); text verbatim; any other type
+    MUST fail — never silent coercion. bool is an int subclass sqlite never
+    emits, guarded explicitly so a stray one can never render as str(True).
+    """
+    if value is None:
+        return ""
+    if isinstance(value, bool):
+        raise RenderError(f"unsupported SQL cell type bool ({value!r}) — never silent coercion")
+    if isinstance(value, int):
+        return str(value)
+    if isinstance(value, float):
+        return repr(value)
+    if isinstance(value, str):
+        return value
+    raise RenderError(
+        f"unsupported SQL cell type {type(value).__name__} — spec §5 allows "
+        "integer/float/text/NULL only; never silent coercion"
+    )
+
+
+def _escape_cell(value: str) -> str:
+    # Escape order is load-bearing: `\` FIRST (else the backslash introduced
+    # by pipe-escaping gets double-escaped), then `|`, then newlines → single
+    # space with CRLF treated as ONE unit.
+    value = value.replace("\\", "\\\\").replace("|", "\\|")
+    return value.replace("\r\n", " ").replace("\r", " ").replace("\n", " ")
+
+
+def render_table(header: Sequence[str], rows: Sequence[Sequence[str]]) -> str:
+    """Render extraction rows as the §5 markdown-table body.
+
+    Cells are strings by the time they reach here (sql values via
+    sql_value_to_text). Header cells are escaped identically to data cells.
+    LF-only, exactly one trailing newline.
+    """
+
+    def line(cells: Sequence[str]) -> str:
+        return "| " + " | ".join(_escape_cell(cell) for cell in cells) + " |"
+
+    separator = "| " + " | ".join("---" for _ in header) + " |"
+    return "\n".join([line(header), separator, *(line(row) for row in rows)]) + "\n"
+
+
+def render_fenced_block(body: str) -> str:
+    """Render an http response body verbatim inside a fenced code block (§5).
+
+    NOT table-escaped — pipe/backslash survive verbatim. The body's own
+    trailing newlines are stripped so the closing fence sits flush; LF-only,
+    exactly one trailing newline.
+    """
+    return f"```\n{body.rstrip(chr(10))}\n```\n"